As the title would suggest threads of my underwear seem to keep sticking to the glans of my penis. I Don't know if its because my glans is wet after peeing?

If that is the case do you use a piece of toilet paper to dry your penis after peeing?

But the main thing here is that with various underwear i get threads sticking to the glans. Each time i go to pee theres always pieces of black or small threads stuck on to my glans or any other place of same region.

Unless it is causing irritation, I wouldn't worry about it much. This is just something that happens. If it's getting irritated then yes, you do have a reason to dry it off before it gets stuck to fabric (tearing off the fabric the first time is the most irritating part). (You aren't diabetic, by any chance, are you? Whether you are or not, it might help to eat less sugar.)

Personally yes, I sometimes do feel like drying off the last drop of pee with a tiny piece of toilet paper. I do it mostly just as a courtesy for my partner who gives me oral sex a lot, but there are actually reasons that toilet paper could be a lot more irritating for some than the fabric of clothes. I also pull my foreskin back to pee, because I don't like the idea of urine residue getting under my foreskin. I don't know how common this is, but I would recommend doing that--if you have foreskin.

I think it sounds like a good way of getting drops of urine all over the place, but apparently most men just gently shake their penis once or twice after they're done urinating.